What Is a Hard Bounce?
A hard bounce occurs when an email is permanently undeliverable to a recipient’s address. Unlike soft bounces (which are temporary issues), hard bounces signal that retrying will not succeed.
This means the email address is no longer valid for delivery, and continuing to send to it could damage your sender reputation.
Common Causes of Hard Bounces
Hard bounces happen for several reasons, including:
Invalid Email Address – The email is mistyped, incorrectly formatted, or simply doesn’t exist.
Non-existent Domain – The domain in the address (e.g., @example.com) no longer exists or has expired.
Recipient Email Server Block – The receiving server blocks delivery due to strict security policies or blacklisting.
Account Closure – The email account has been closed or deleted by the user or provider.
Note:
A hard bounce indicates an email address that no longer exists.
If that address later starts receiving mail with clicks, it may have been converted into a spam trap.
In rare cases, if a mailbox provider restores the account, they’ll send us a special header code, and we’ll automatically reset the mailbox for you.
Managing Hard Bounces
Properly managing hard bounces is critical for keeping your email program healthy. Here are key strategies:
Regular List Cleaning
Remove invalid or inactive addresses every 30–60 days.
This reduces the chance of sending to traps or expired addresses.
Use Double Opt-In
Confirm subscriptions with a second verification step.
This ensures that only valid, engaged email addresses enter your list.
Monitor Bounce Rates
Keep track of your bounce rates in every campaign.
High bounce rates can negatively affect deliverability and trigger filtering by inbox providers.
Segment and Test
If a particular source or signup form produces high bounce rates, investigate and adjust.
Why Managing Hard Bounces Matters
Protects Your Reputation – Fewer invalid sends mean fewer negative signals to inbox providers.
Improves Deliverability – Keeping your list clean helps you reach more inboxes.
Boosts Engagement – Valid contacts mean better open and click rates.
Saves Costs – Avoid wasting resources on undeliverable addresses.
Conclusion
Understanding and managing hard bounces is a critical aspect of successful email marketing. By recognizing the causes and implementing prevention strategies like regular list cleaning and double opt-in, you’ll maintain a healthier list, safeguard your sender reputation, and improve overall deliverability.